Amputees commonly use prosthetic devices to improve their mobility and associated quality of life. Various types of prostheses exist for replacing the functionality of a missing limb. Transtibial and transfemoral prostheses are effective at helping amputees regain the ability to walk on their own. Various forces cause separation between a prosthetic limb and a residual limb, especially during use. This may happen, for example, during the swing phase of ambulation, when a prosthetic leg is subjected to both gravitational and centrifugal forces. The manner in which an artificial limb is attached to a residual limb determines the control an amputee has over the prosthesis.
Amputees can secure prosthetic devices on their residual limbs by using various vacuum or suction arrangements, whereby the maximum strength of the force holding the prosthesis to the residual limb is a function of the atmospheric pressure. The differential air pressure is routinely referred to as suction or vacuum by those having skill in the art. To maintain the sub-atmospheric pressure created within the distal end of the socket, sealing sleeves or liners have been provided to prevent an influx of air around the distal end of the residual limb. Such liners are provided between the residual limb and the socket to provide for slight compression, and a gripping connection is provided to assist with the suction suspension.
The liner can be rolled onto the residual limb so the liner-covered limb can then be inserted into the socket. The use of conventional liners alone only provides a partial suction fit since they do not form a true air-tight seal with the socket. Some air will slowly enter the socket, especially during the swing phase of the patient's gait and during periods of inactivity.
Conventional vacuum systems have been used to increase the suction within the socket. Such vacuum systems may utilize a valve at a distal end of an otherwise closed socket arranged to receive the distal end portion of a residual limb. These systems work by exhausting air only from the space between the distal end of the residual limb and the distal end of the socket interior as the limb is fully inserted into the socket. Any air that has migrated to areas other than the distal end can remain trapped, and this action affects the optimal pressure differential and diminishes the strength of the suction connection. There is a clear need to provide a way to allow a user to expel air from within any area of the socket.
The use of a valve is intended to allow air to be expelled from the socket in order to maintain at least a slight negative pressure for creating suction against the residual limb. Although the swing phase of the gait cycle will tend to pull the socket off the limb, walking and other weight-bearing activities may push the limb further into the socket. Pushing the limb further into the socket causes the valve to expel air. Conversely, directly pulling the limb out of the socket is prohibited due to the effect of suction.
Using a valve alone may not be an effective or efficient way to expel excess air from within the socket. Many conventional vacuum suspension systems consequently include a vacuum pump to create the desired vacuum effect.
Current vacuum pumps used with prosthetic sockets have several disadvantages, including their size, weight and difficulty of use. For many patients, the time-consuming steps involved with operating the pump combined with the cumbersome placement and unreliability of accurately regulating pressure convinces them to avoid using prostheses entirely.
It can be seen from the foregoing there are many needs for improving on the drawbacks of conventional vacuum suspension systems for attaching to prosthetic sockets. The embodiments of the present disclosure address these aforementioned shortcomings of known prosthetic systems.